Adding idelalisib to rituximab significantly extends survival in patients with heavily pretreated relapsed chronic lymphocytic leukemia unsuitable for chemotherapy, according to published results from Study 116.
The primary endpoint of median progression-free survival (PFS) was 5.5 months with rituximab (Rituxan) plus placebo and had not been reached with rituximab plus idelalisib (hazard ratio, 0.15; P less than .0001).
The PFS advantage was seen across all subgroups including patients with the 17p deletion and TP53 mutations, Dr. Richard R. Furman reported at the annual meeting of the American Society of Hematology in December. The final results of the study were published online January 22 in the New England Journal of Medicine.
Overall survival was not reached in either group, but was also significantly longer with idelalisib (HR, 0.28; P = .018).
The investigators evenly randomized 220 patients to eight infusions of rituximab over 24 weeks plus either idelalisib 150 mg or placebo twice daily until disease progression. Rituximab was dosed at 375 mg/m2 in week 1, 500 mg/m2 every 2 weeks for four doses, followed by 500 mg/m2 every 4 weeks for three more doses.